Machine and method for acquiring data for measuring the twist and concavity of agricultural discs

ABSTRACT

The machine is used to automatically measure both the twist and concavity of agricultural discs with a high level of precision. Currently, in order to calculate such measurements, dial indicators are used to investigate whether twist and concavity variables are within pre-established tolerances. This conventional methodology is slow and imprecise. In order to measure twist and concavity according to the invention, the agricultural disc is rotated and data is recorded along the periphery of the disc using a laser measurement device, by means of which a previously recorded central reference point is also determined, by comparing the resulting values in terms of height.

OBJECT OF THE INVENTION

The present invention, as expressed in this descriptive specification, relates to a machine and method for acquiring data for measuring the twist and concavity of agricultural discs.

The machine is designed to measure both the twist and the concavity of agricultural discs, quickly and automatically, with a high level of precision, by means of a laser measurement device built into it.

The twist and concavity of the agricultural discs are measured in order to comply with pre-established technical specifications, used to check the quality of the end product obtained.

BACKGROUND OF THE INVENTION

At the moment, agricultural discs must be submitted to quality control tests once they have been manufactured. These tests check whether or not the agricultural discs manufactured comply with a number of pre-established technical specifications.

The technical specifications to be revised include those related to twist and concavity at the disc surface.

Currently, said specifications are usually measured manually by means of a dial indicator. This instrument is used to test twist and concavity, determining whether or not these variables fall within established tolerance levels.

This method is very slow if large amounts of measurements are to be made, owing to the limitations posed by the agricultural disc fastener used to make said measurements.

Likewise, the precision with which this method is carried out depends on the skill of the person using the dial indicator.

DESCRIPTION OF THE INVENTION

With the aim of achieving the aims and avoiding the limitations set out above, the first object of the invention constitutes a machine for acquiring data for measuring the twist and concavity of agricultural discs, comprising:

-   -   a rotational mounting bracket, upon which an agricultural disc         is supported and held.     -   a hold-down plate free to rotate, arranged above the mounting         bracket, both elements being opposite one another in the same         vertical direction.     -   a linear actuator, which travels vertically in a downwards         direction towards the hold-down plate, pressing the same down         and butting against a central area of an upper surface of the         agricultural disc placed on the mounting bracket, whilst in         other positions above the hold-down plate, the same is distanced         from the agricultural disc.     -   a laser measurement device, arranged above the agricultural disc         to be measured, which in turn, is coupled to a linear guide         arranged in a direction perpendicular to the vertical direction         in which the hold-down plate travels, which coincides with the         vertical direction around which the mounting bracket rotates.     -   a frame, upon which the various elements of the machine are         supported.

Once the agricultural disc has been immobilised and is held between the mounting bracket arranged below and the hold-down plate arranged above, said agricultural disc is made to rotate by means of the rotational activation of the mounting bracket.

In one embodiment of the invention, the location of the agricultural disc comprises a space delimited by a rear protection surface, two side surfaces and a table platform, above which the mounting bracket protrudes.

The table platform is joined to some legs, which form part of the frame of the machine, object of the invention.

The hold-down plate forms part of a rotational head-piece, fixed to the rod of a vertical cylinder by means of a female sleeve, said vertical cylinder constituting the linear actuator for vertically displacing the hold-down plate.

Moreover, the rotational head-piece comprises a lower fixation sleeve, upon which the hold-down plate is supported; an upper fixation sleeve, coupled to the female sleeve and; an intermediate axial load ball bearing, placed between both fixation sleeves.

The intermediate ball bearing is housed in a hollow, delimited by an end annular recess in the female sleeve and by circumferential portions of both fixation sleeves, i.e., the upper and lower fixation sleeves, both being joined by means of screws.

Said lower fixation sleeve has at least one built in appendix, wherein the hold-down plate is engaged, which is immobilised by means of a number of set screws, the ends of which fit in a number of blind grooves in the lower fixation sleeve appendix.

The hold-down plate has a first built in annular stop, which presses against the upper face of the agricultural disc to be controlled, whilst the mounting bracket has a second built in annular stop, upon which the agricultural disc is supported on its lower face.

The mounting bracket is built into an actuator device fixed to the machine frame and rotates as a result of being driven by a motor, also fixed to the machine frame.

Said actuator device comprises a casing, fixed to the machine frame, which supports a vertical shaft that rotates as a result of being driven by the aforementioned motor, the mounting bracket being engaged in an upper end stretch of the vertical shaft, whilst said mounting bracket rests against an annular extension of the vertical shaft.

Another characteristic of the invention is that the actuator device have ball bearings, interspersed in the coupling of the vertical shaft, relative to the casing of said actuator device.

It must also be noted that the upper end of the vertical shaft of the actuator device has a housing built into its centre, in which a male element is engaged, where a central perforation of the agricultural disc is adjusted, in addition to a central perforation of a model disc, initially placed in order to determine a central reference point, as shall be described further on.

A second object of the invention relates to a method for acquiring data for measuring the twist and concavity of agricultural discs.

The method comprises the following stages:

-   -   Placing the model disc in the centre of the mounting bracket.     -   Positioning the laser measurement device in a central area of         the model disc, above the same.     -   Rotating the model disc, in order to use the laser measurement         device to obtain reference data, corresponding to points at an         equal distance away from the centre of the model disc, in order         to determine a central reference height corresponding to said         centre of the model disc. These points are measured relative to         a start point in the machine located such that it corresponds         with the laser device, taking the height between each one of         said points relative to the start point cited into account.     -   Once the central reference height has been determined, the model         disc is dismounted and the process for measuring the         agricultural discs continues, each agricultural disc to be         measured being mounted in the centre of the mounting bracket,         ensuring the same is immobilised by means of lowering the         hold-down plate.     -   The laser measurement device is displaced, in order to be         positioned such that it corresponds with the periphery of the         agricultural disc.     -   Measurements are made in order to obtain data (at points along         the perimeter) along the perimeter of the agricultural disc, as         the same rotates, using the laser measurement device.     -   Both the twist and concavity of the agricultural disc are         calculated using the measurement data acquired.

The twist of the agricultural disc calculated corresponds to the difference in height between the maximum and minimum measurements acquired in the data, this measurement data corresponding to the heights measured from the start point of the laser measurement device and 1 the points chosen along the periphery of the agricultural disc, when opposite said start point in the laser measurement device, height values thereby being obtained.

The difference in height between the resulting values obtained is subsequently compared against pre-established tolerance limits, in order to determine whether or not the agricultural disc is valid in terms of twist.

Concavity is measured in accordance with diametral axes in each agricultural disc, in such a way that concavity is calculated taking the measurement data corresponding to height, acquired between several pairs of diametrically opposed peripheral points on the agricultural disc, relative to the start point, into account, in addition to the height of the central reference point.

The following are calculated in accordance with each diametral axis: a first distance between the start point of the laser measurement device and a point along the periphery of the agricultural disc and; a second distance between the start point of the laser device and a diametrically opposed point of the agricultural disc periphery. These distances constitute vertical magnitudes (heights).

The average between the first and second distances is subsequently calculated and said average is then compared to the central reference height of the model disc, the difference between both constituting the concavity of said axis.

Finally, the average of the concavities of the axes measured is found and compared with pre-established tolerance levels, in order to determine whether or not the agricultural disc is valid in terms of concavity.

The reference data pertaining to the model disc is obtained as follows:

-   -   A first piece of data is taken prior to setting the model disc         into rotational motion.     -   A second piece of data is taken as the agricultural disc moves         rotationally at 0.9 seconds.     -   A third piece of data is taken at 1.8 seconds, keeping the         agricultural disc in rotational movement.     -   A fourth piece of data is taken at 2.7 seconds, keeping said         agricultural disc in rotational motion.

The measurement data (points) chosen along the periphery of the agricultural disc are taken by rotating the agricultural disc by one full turn, plus a portion of a second turn, with a time interval of at least 0.001 seconds.

Of the measurement data obtained, a few pieces of specific data are chosen, in order to calculate concavity, these pieces of data being chosen as follows:

-   -   A first piece of data, which is chosen at 0.8 seconds after         beginning to rotate the agricultural disc.     -   A second piece of data, collected at 1.465 seconds.     -   A third piece of data, collected at 2.13 seconds.     -   A fourth piece of data, collected at 2.795 seconds.     -   A fifth piece of data, collected at 3.46 seconds.     -   A sixth piece of data, collected at 3.325 seconds.

Below, in order to facilitate better understanding of the present descriptive specification, a number of drawings are attached, which form an integral part of the same and provide a non-limiting illustration of the object of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1.—Is a perspective view of the machine for acquiring data for measuring the twist and concavity of agricultural discs.

FIG. 2.—Is a cross-section of a rotational head and hold-down plate assembly.

FIG. 3.—Is a cross-section of an actuator device, with a built-in vertical shaft, the upper end of which is fixed to the mounting bracket, the assembly formed by said vertical shaft and the mounting bracket being rotated by means of a motor.

FIG. 4.—Is a plan view of a model disc, initially used to identify a central reference point.

FIG. 5.—Is a plan view of an agricultural disc with various reference points around the perimeter.

FIGS. 6 and 7.—Are schematic views providing a basic representation of the system for measuring twist and concavity, by taking data at the periphery of the agricultural disc, in addition to a central reference point that corresponds to the centre of said agricultural disc.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT OF THE INVENTION

The machine for acquiring data for measuring the twist and concavity of agricultural discs comprises the following elements, listed according to the numbering adopted in the drawings:

-   1.—Frame -   2.—Vertical cylinder -   3.—Hold-down plate -   3 a.—First annular end -   4.—Linear guide -   5.—Laser measurement device -   6.—Table platform -   6 a.—Hole -   7.—Actuator device -   8.—Motor -   9.—Rear protection surface -   10.—Side protection surface -   11.—Side protection surface -   12.—Legs -   13.—Mounting bracket -   13 a.—Second annular end -   14.—Rod -   15.—Female sleeve -   15 a.—End annular recess -   16.—Intermediate ball bearing -   17.—Upper fixation sleeve -   17 a.—Circumferential portion -   18.—Lower fixation sleeve -   18 a. Circumferential portion -   19.—Screws -   20.—Appendix -   20 a.—Blind grooves -   21.—Rotational head-piece -   22.—Set screws -   23.—Vertical shaft -   23 a.—Annular extension -   24.—Casing -   25.—Ball bearings -   26.—Housing -   27.—Male element -   28.—Agricultural disc -   28 a.—Central perforation -   29.—Model disc -   29 a.—Central perforation

In principle, it comprises a frame 1, a rear protection surface 9 and two side protection surfaces 10-11, which define a frontally open surrounding space.

A vertical cylinder 2 is installed in the upper area on said frame 1, which may be pneumatic or hydraulic and is responsible for driving a hold-down plate 3 that forms part of a rotational head-piece 21 connected to the rod 14 of the vertical cylinder 2 by means of a female sleeve 15, which threads onto said rod 14. Likewise, a linear guide 4 is fixed onto said frame 1, upon which a laser measurement device 5 is displaced.

Furthermore, the machine has a table platform 6 supported by means of legs 12, said legs 12 in turn being supported on the machine frame 1 itself.

An actuator device 7 is mounted to the lower portion of this frame 1, a mounting bracket 13 protruding from said actuator device 7 through a hole 6 a made in the table platform 6.

The female sleeve 15 has an end annular recess 15 a, in which an intermediate axial load ball bearing 16 is inserted, the same being held by means of using two fixation sleeves, namely an upper 17 fixation sleeve and a lower 18 fixation sleeve, both being joined by means of screws 19.

Said intermediate ball bearing 16 is housed in a hollow delimited by the end annular recess 15 a in the female sleeve and by circumferential portions 17 a and 18 a of both fixation sleeves, namely the upper 17 and lower 18 fixation sleeves, respectively.

The lower fixation sleeve 18 has an appendix 20 to which the hold-down plate 3 is coupled by means of screws 22, the ends of which fit into a number of blind grooves 20 a in the appendix 20 of the lower fixation sleeve 18.

The rotational head-piece 21 in turn comprises the two fixation sleeves, i.e. the upper 17 and lower 18 fixation sleeves, alongside the hold-down plate 3.

In turn, the actuator device 7 is formed by a casing 24, which is fixed to the frame 1. Inside said casing 24, there is a vertical shaft 23, supported by ball bearings 25. In correspondence with the lower end of the vertical shaft 23, a motor 8 is coupled, which provides said vertical shaft 23 and as such, the mounting bracket 13, with rotational movement.

In contrast, the upper end of the vertical shaft 23 is inserted into the mounting bracket 13, which has a housing 26 at its centre, in order for a male element 27 to be inserted therein, where a central perforation 28 a of the agricultural disc 28 to be measured is adjusted, a perforation 29 a of a model disc 29 initially placed on the mounting bracket 13 also being adjusted.

It must also be noted that the mounting bracket 13 is supported against an annular extension 23 a of the vertical shaft 23.

Having sufficiently described the structure of the machine, object of the invention, we shall now go on to describe how said machine works.

The agricultural disc to be measured is inserted into the male element 23, whilst it is supported against the mounting bracket 13. The vertical cylinder 2 is subsequently driven, the hold-down plate 3 therefore being lowered until an annular stop 3 a of said hold-down plate 3 comes into contact with the agricultural disc 28, fixing it against the mounting bracket 13.

The motor 8 drives the rotation of the vertical shaft 23, also making the mounting bracket 13 rotate jointly and, the hold on the agricultural disc 28 provided by the hold-down plate 3 onto said mounting bracket means that activating said motor 8 also causes the rotational head-piece 21 assembly including the hold-down plate 3 to be pulled.

The laser measurement device 5 takes data measurements as the agricultural disc 28 rotates.

The data taken by the laser measurement device 5 is stored in a PLC, in order to subsequently calculate the twist and concavity of the agricultural disc 28 using a computer program, thereby checking whether or not said agricultural disc 28 complies with the required specifications previously set down.

Should the disc fall within the required tolerance limits, the machine will emit a green light, whilst if it does not, the same will emit a red light.

The method for acquiring data for measuring the twist and concavity of agricultural discs is as follows:

Firstly, at the start of the day, a central reference height is measured using the model disc 29, in accordance with a central point “X” on said model disc 29.

In order to do so, the laser measurement device 5 is positioned via the linear guide 4, such that it corresponds with the central area of the model disc 29 fitted onto the male element 27 by means of its central perforation 29 a, the hold-down plate being kept in an upper position.

In said position, the model disc 29 is made to rotate and reference data corresponding to four points a-b-c-d at an equal distance from the centre of said model disc 29 are taken, in order to determine the central reference height. Said points are measured relative to a start point “Z” in the machine, located such that it corresponds with the laser measurement device 5, the heights between each one of said points relative to said start point “Z” being taken into account, the average value of said heights corresponding to said reference data subsequently being calculated, in order to thus obtain the central reference height of the model disc 29.

Said reference data is acquired as follows:

-   -   a first piece of data “a” is taken before beginning to rotate         the model disc 29.     -   The model disc 29 is then set into rotational motion.     -   A second piece of data “b” is taken at 0.9 seconds.     -   A third piece of data “c” is taken at 1.8 seconds.     -   A fourth piece of data “d” is taken at 2.7 seconds.

Once the central reference height has been calculated, the model disc 29 is dismounted and each agricultural disc 28 to be measured is mounted, a number of pieces of measurement data being taken for the different agricultural discs 28 to be measured, in order to calculate the twist and concavity, this measurement data corresponding to the heights measured from the start point “Z” of the laser measurement device 5 and each one of the points along the periphery of the corresponding agricultural disc 28.

In order to calculate concavity and twist, the laser measurement device 5 is displaced via the linear guide 4 to the periphery of the agricultural disc 28 to be measured, where it will collect data corresponding to the periphery (points along the perimeter) of said agricultural disc 28 at very short time intervals of at least 0.001 seconds.

Of the data acquired in previous steps, six pieces of measurement data corresponding to specific points (A, B, C, D, E and F) are used to calculate concavity, which correspond to three diametral axes of the agricultural disc 28: A-D, B-E and C-F.

When the agricultural disc begins to rotate, 0.8 seconds pass without collecting or taking data. Subsequently, the data used to calculate concavity is collected as follows, as the agricultural disc 28 is in rotational movement:

-   -   Data “A” is collected at 0.8 seconds after beginning to rotate         the agricultural disc 28.     -   Data “B” is collected at 1.465 seconds.     -   Data “C” is collected at 2.13 seconds.     -   Data “D” is collected at 2.795 seconds.     -   Data “E” is collected at 3.46 seconds.     -   Data “F” is collected at 3.325 seconds.

Once the laser measurement device 5 has collected the last piece of data, the agricultural disc 28 continues to rotate for a further 1.465 seconds, until the hold-down plate 3 is lifted.

All of the data is collected by rotating the agricultural disc 28 by one full turn, plus a portion of a second turn on the mounting bracket 13.

The laser measurement device 5 collects data as follows: a laser diode emits a beam, which crosses an emitter lens and crashes against the upper surface of the agricultural disc 28. The beam reflected from the agricultural disc 28 is subsequently collected by a reflective lens and sent to a sensor, which detects the intensity peak, thereby establishing the distance from the agricultural disc 28.

The twist of the agricultural disc 28 is calculated in accordance with the data collected and corresponds to the difference in height (the direction perpendicular to the plane of said agricultural disc 28) between the maximum and minimum values of all the measurement data acquired along the periphery of the agricultural disc.

In contrast, the concavity of the agricultural disc 28, in accordance with the data collected, is calculated as follows:

First of all, in one embodiment of the invention, the concavity of three diametral axes of the agricultural disc 28 are calculated:

Concavity  of  a  first  axis: $({AD}) = {\frac{{{distancia}\mspace{11mu} ({ZA})} + {{distancia}\mspace{11mu} ({ZD})}}{2} - {{distancia}\mspace{11mu} ({ZX})}}$ Concavity  of  a  second  axis: $({BE}) = {\frac{{{distancia}\mspace{11mu} ({ZB})} + {{distancia}\mspace{11mu} ({ZE})}}{2} - {{distancia}\mspace{11mu} ({ZX})}}$ Concavity  of  a  third  axis: $({CF}) = {\frac{{{distancia}\mspace{11mu} ({ZC})} + {{distancia}\mspace{11mu} ({ZF})}}{2} - {{distancia}\mspace{11mu} ({ZX})}}$

where “X” refers to the central reference point of the model disc 29, whilst “Z” refers to a start point at coordinates of the machine located such that they correspond with the laser measurement device 5, the distance (ZX) constituting the central reference height.

The concavities of the three axes is then measured, thereby obtaining the concavity of the agricultural disc.

Said values, corresponding to both concavity and twist, are comparted with their respective tolerance values, thereby deciding whether or not the piece is acceptable.

As such, the machine and measurement method object of the invention reduce testing time (the time it takes the disc to complete one full turn) and increase precision, given that said testing does not rely on human ability.

Furthermore, using the data acquired, it is possible to check whether or not the manufacturing process employed to make the agricultural discs complies with the desired technical specifications.

As such, using the corresponding formula, it is possible to obtain short-term capacity indices, which indicate how suitable the manufacturing process is. 

1-17. (canceled)
 18. A machine for acquiring data for measuring the twist and concavity of agricultural discs, designed for measuring the twist and concavity of agricultural discs, with a frame (1) that supports the various elements in the machine, characterised in that it comprises: a rotational mounting bracket (13), upon which an agricultural disc (28) is supported and held; a hold-down plate (3) that can rotate freely, arranged above the mounting bracket (13), both elements being located opposite one another (3,13) in the same vertical direction; a linear actuator, which displaces vertically in a downwards direction towards the hold-down plate (3), where, when the hold-down plate (3) is in a lower end position, the same presses and buts against a central area of the agricultural disc (28) placed on the mounting bracket (13), whilst, when said hold-down plate (3) is in other upper positions, the same is distanced from the agricultural disc (28); a laser measurement device (5), arranged above the agricultural disc (28) to be measured, in turn coupled to a linear guide (4), arranged in a direction perpendicular to the vertical direction in which the hold-down plate (3) travels, which coincides with the vertical direction around which the mounting bracket (13) rotates, where: the hold-down plate (3) forms part of a rotational head-piece (21) fixed to a rod (14) of a vertical cylinder (2) by means of a female sleeve (15), the vertical cylinder (2) constituting the linear actuator used to displace the hold-down plate (3) vertically; the rotational head-piece (21) comprising a lower fixation sleeve (18) upon which the hold-down plate (3) is supported, an upper fixation sleeve (17) coupled to the female sleeve (15) and an intermediate axial load ball bearing (16) interspersed between both fixation sleeves (17,18); the intermediate ball bearing (16) being housed in a hollow delimited by an end annular recess (15 a) in the female sleeve (15) and by circumferential portions (17 a, 18 a) of both fixation sleeves: the upper (17) and lower (18) fixation sleeves; the two fixation sleeves (17, 18) being joined by screws (19).
 19. The machine for acquiring data for measuring the twist and concavity of agricultural discs according to claim 18, characterised in that: the location of the agricultural disc (28) comprises a space delimited by a rear protection surface (9), two side surfaces (10,11) and a table platform (6), above which the mounting bracket (13) protrudes; the table platform (6) is linked to legs (12), which form part of the frame (1).
 20. The machine for acquiring data for measuring the twist and concavity of agricultural discs according to claim 18, characterised in that: the lower fixation sleeve (18) has at least one appendix (20), in which the hold-down plate (3) is engaged and; the hold-down plate (3) is immobilised by means of screws (22), the ends of which fit into blind grooves (20 a) in the appendix (20) of the lower fixation sleeve (18).
 21. The machine for acquiring data for measuring the twist and concavity of agricultural discs according to claim 18, characterised in that: the hold-down plate (3) has a first annular end (3 a), which presses against the upper face of the agricultural disc (28) to be submitted to control; the mounting bracket (13) has a second annular end (13 a), upon which the agricultural disc (28) is supported at its lower face.
 22. The machine for acquiring data for measuring the twist and concavity of agricultural discs according to claim 18, characterised in that: the mounting bracket (13) is built into an actuator device (7) fixed to the frame (1) of the machine; the mounting bracket (13) rotates being driven by a motor (8), also fixed to the frame (1).
 23. The machine for acquiring data for measuring the twist and concavity of agricultural discs according to claim 22, characterised in that: the actuator device (7) comprises a casing (24) fixed to the frame (1), which supports a vertical shaft (23) that rotates being driven by the motor (8); the mounting bracket (13) is built into an upper end stretch of the vertical shaft (23) and; the mounting bracket (13) is supported against an annular extension (23 a) of the vertical shaft (23).
 24. The machine for acquiring data for measuring the twist and concavity of agricultural discs according to claim 23, characterised in that the actuator device (7) has ball bearings (25), which are interspersed in the coupling of the vertical shaft (23) relative to the casing (24).
 25. The machine for acquiring data for measuring the twist and concavity of agricultural discs according to claim 23, characterised in that the upper end of the vertical shaft (23) of the actuator device (7) has a housing (26) at its centre, in which a male element (27) is engaged, where a central perforation (28 a) of the agricultural disc (28) and a central perforation (29 a) of a model disc (29) are adjusted.
 26. A method for acquiring data for measuring the twist and concavity of agricultural discs, carried out by the machine described in claim 18, characterised in that it comprises the following stages: placing the model disc (29) in the centre of the mounting bracket (13); positioning the laser measurement device (5) in a central area of the model disc (29) above the same; making the model disc (29) rotate in order to use the laser measurement device (5) to obtain reference data corresponding to points a-b-c-d, which are equidistant from the centre of the model disc (29), in order to determine a central reference height that corresponds to said centre of the model disc (29), the points equidistant from the centre of the model disc (29) being taken relative to a start point “Z” of the machine, located in correspondence with the laser measurement device (5), the height between each one of said points being taken into account, relative to the start point “Z”; one the height of the central reference point has been obtained, demounting the model disc (29) and continuing with the process for measuring agricultural discs (28) by mounting each agricultural disc (28) to be measured centrally on the mounting bracket (13), ensuring it is immobilised by means of lowering the hold-down plate (3); displacing the laser measurement device (5) in order to position it such that it corresponds with the periphery of the agricultural disc (28), using the laser measurement device (5) to take measurement data that corresponds to the heights between the start point “Z” and each one of the points chosen along the periphery of the agricultural disc (28) as it is rotated.
 27. The method for acquiring data for measuring the twist and concavity of agricultural discs according to claim 26, characterised in that: the twist of the agricultural disc (28) is calculated according to the difference in height between the maximum and minimum data measurements acquired, these pieces of measurement data corresponding to the relative height between the start point “Z” of the laser measurement device (5) and the points along the periphery of the agricultural disc (28), when they are opposite said start point “Z” of the laser measurement device (5), thus obtaining resulting values; the difference in height between these resulting values obtained is compared to pre-established tolerance levels, in order to determine whether or not the agricultural disc (28) is valid in terms of the twist variable.
 28. The method for acquiring data for measuring the twist and concavity of agricultural discs according to claim 26, characterised in that: concavity is measured on diametral axes of the agricultural disc (28), taking the height measurement data acquired between various pairs of diametrically opposed peripheral points of the agricultural disc into account, relative to the start point “Z” and the central reference height; in accordance with each diametral axis, the following is calculated: a first distance between the start point “Z” of the laser measurement device (5) and a point along the periphery of the agricultural disc (28) and; a second distance between the start point “Z” of the laser measuring device (5) and a diametrically opposed point along the periphery of the agricultural disc (28); the average between the first and second distances being calculated on each diametral axis, said average then being compared to the central reference height of the model disc (29), the difference between both constituting the concavity of said axis; the average of the concavities obtained in correspondence to the various diametral axes of the agricultural disc (28) then being taken (28); and the average of the concavities obtained being compared to pre-established tolerance levels, in order to determine whether or not the agricultural disc (28) is valid.
 29. The method for acquiring data for measuring the twist and concavity of agricultural discs according to claim 26, characterised in that the reference data pertaining to the model disc (29) is taken as follows: a first piece of data “a” is taken before beginning to rotate the model disc (29); a second piece of data “b” is taken at 0.9 seconds; a third piece of data “c” is taken at 1.8 seconds; and a fourth piece of data “d” is taken at 2.7 seconds.
 30. The method for acquiring data for measuring the twist and concavity of agricultural discs according to claim 26, characterised in that the measurement data taken in correspondence with the periphery of the agricultural disc (28) in order to calculate concavity is taken as follows: a first piece of data “A” is taken at 0.8 seconds after beginning to rotate the agricultural disc (28); a second piece of data “B” is taken at 1.465 seconds; a third piece of data “C” is taken at 2.13 seconds; a fourth piece of data “D” is taken at 2.795 seconds; a fifth piece of data “E” is taken at 3.46 seconds; a sixth piece of data “F” is taken at 3.325 seconds; once the laser measurement device (5) has taken the last measurement data from the agricultural disc (28), the same continues to rotate for a further 1.465 seconds, until the hold-down plate (3) is lifted.
 31. The method for acquiring data for measuring the twist and concavity of agricultural DISCS according to 26, characterised in that all of the measurement data pertaining to the agricultural disc (28) is collected by rotating the agricultural disc (28) by one full turn, plus a section of a second turn, with a time interval of at least 0.001 seconds.
 32. The method for acquiring data for measuring the twist and concavity of agricultural discs according to claim 26, characterised in that the laser measurement device (5) takes the data from a laser diode that emits a beam that crosses an emitting lens, which bumps against the upper surface of the agricultural disc (28), in order for the beam to subsequently be reflected from the agricultural disc (28) and be collected by a receptor lens, said beam then being sent to a sensor, which detects the intensity peak by establishing distance from the agricultural disc (28).
 33. The machine for acquiring data for measuring the twist and concavity of agricultural discs according to claim 24, characterised in that the upper end of the vertical shaft (23) of the actuator device (7) has a housing (26) at its centre, in which a male element (27) is engaged, where a central perforation (28 a) of the agricultural disc (28) and a central perforation (29 a) of a model disc (29) are adjusted.
 34. The method for acquiring data for measuring the twist and concavity of agricultural DISCS according to 27, characterised in that all of the measurement data pertaining to the agricultural disc (28) is collected by rotating the agricultural disc (28) by one full turn, plus a section of a second turn, with a time interval of at least 0.001 seconds.
 35. The method for acquiring data for measuring the twist and concavity of agricultural DISCS according to 28, characterised in that all of the measurement data pertaining to the agricultural disc (28) is collected by rotating the agricultural disc (28) by one full turn, plus a section of a second turn, with a time interval of at least 0.001 seconds.
 36. The method for acquiring data for measuring the twist and concavity of agricultural DISCS according to 29, characterised in that all of the measurement data pertaining to the agricultural disc (28) is collected by rotating the agricultural disc (28) by one full turn, plus a section of a second turn, with a time interval of at least 0.001 seconds.
 37. The method for acquiring data for measuring the twist and concavity of agricultural DISCS according to 30, characterised in that all of the measurement data pertaining to the agricultural disc (28) is collected by rotating the agricultural disc (28) by one full turn, plus a section of a second turn, with a time interval of at least 0.001 seconds. 